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Hydrodynamics of salt flat basins: The Salar de Atacama example
- Source :
- Digital.CSIC. Repositorio Institucional del CSIC, instname
- Publication Year :
- 2018
-
Abstract
- The Salar de Atacama is one of the most well-known saline endorheic basins in the world. It accumulates the world main lithium reserves and contains very sensitive ecosystems. The objective of this work is to characterize the hydrodynamics of the Salar de Atacama, and to quantify its complex water balance prior to the intense brine extraction. The methodology and results can be extrapolated to the groundwater flow and recharge of other salt flats. A three-dimensional groundwater flow model using low computational effort was calibrated against hundreds of hydraulic head measurements. The water infiltrated from the mountains ascends as a vertical flux through the saline interface (mixing zone) produced by the density contrast between the recharged freshwater and the evaporated brine of the salt flat nucleus. This water discharges and is largely evaporated from lakes or directly from the shallow water table. On the other hand, the very low hydraulic gradients, coupled with the presence of the mixing zone that operates as barrier, leads the salt flat nucleus to act as a hydrodynamically quasi-isolated area. The computed water table shows the lowest hydraulic head in the salt flat nucleus near the discharge at the mixing zone. The groundwater balance of the Salar de Atacama in its natural regime was quantified resulting in an inflow/outflow of 14.9 m3·s−1. This balance considers the basin as an endorheic system. The very low infiltration values that are generally assumed for hyperarid basins are not consistent with the hydrogeology of the Salar de Atacama. Indeed, very high infiltration rates (up to 85% of rainfall) occur because of the high degree of fracturing of rocks and the scarce vegetation. This high infiltration is consistent with the light isotopic composition of the water from the recharge area (Altiplano). Therefore, the existence of additional inflows outside the basin is unlikely. © 2018<br />The authors acknowledge Sociedad Química y Minera de Chile S.A. (SQM) for their support and sharing data throughout the hydrogeological characterization of the SdA site. M.A. Marazuela gratefully acknowledges the financial support from the AGAUR (Agència de Gestió d'Ajuts Universitaris I de Recerca, Generalitat de Catalunya) and the European Union (grant number 2017FI B1 00194). Finally, we thank three anonymous reviewers for their valuable comments.
- Subjects :
- Salt pan
Brine
Saltwater intrusion
Environmental Engineering
010504 meteorology & atmospheric sciences
Groundwater flow
Water table
Lithium
010501 environmental sciences
Structural basin
01 natural sciences
Numerical model
Groundwater recharge
Water balance
Environmental Chemistry
Waste Management and Disposal
0105 earth and related environmental sciences
Hydrology
geography
geography.geographical_feature_category
Pollution
Groundwater
Geology
Subjects
Details
- ISSN :
- 18791026
- Volume :
- 651
- Issue :
- Pt 1
- Database :
- OpenAIRE
- Journal :
- The Science of the total environment
- Accession number :
- edsair.doi.dedup.....86ad4ea28b10d8ede5f1a2d298fe8521